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Abstract:

A power generating apparatus of renewable energy type includes a tower, a
nacelle which is supported rotatably by a tip portion of the tower; a
main shaft rotatable with a blade; a hydraulic pump which is housed in
the nacelle and is driven by rotation of the main shaft; a hydraulic
motor which is driven by operating oil supplied from the hydraulic pump;
a generator which is coupled to the hydraulic motor; an operating-oil
line which is provided between the hydraulic pump and the hydraulic motor
and through which the operating oil circulates; a cooling-medium line
through which cooling medium for cooling the operating oil circulates via
an intermediate heat exchanger; and a main heat exchanger which cools the
cooling medium by heat exchange with cool water source around a base
portion of the tower, and one of the operating-oil line.

Claims:

1. A power generating apparatus of renewable energy type which generates
power from renewable energy, comprising: a tower; a nacelle which is
supported rotatably by a tip portion of the tower; a main shaft which is
housed in the nacelle and rotates with a blade; a hydraulic pump which is
housed in the nacelle and is driven by rotation of the main shaft; a
hydraulic motor which is driven by operating oil supplied from the
hydraulic pump; a generator which is coupled to the hydraulic motor; an
operating-oil line which is provided between the hydraulic pump and the
hydraulic motor and through which the operating oil circulates; a
cooling-medium line through which cooling medium for cooling the
operating oil circulates via an intermediate heat exchanger; and a main
heat exchanger which cools the cooling medium by heat exchange with cool
water source which is one of sea water, lake water, river water and
groundwater around a base portion of the tower, wherein one of the
operating-oil line and the cooling-medium line comprises: a first piping
which is supported on a nacelle side; a second piping which is supported
on a tower side; and a connection part which connects the first piping
and the second piping so that the first piping and the second piping are
relatively rotatable.

2. The power generating apparatus of renewable energy type according to
claim 1, wherein the hydraulic motor is provided between the tip portion
and the base portion of the tower, wherein the operating-oil line extends
between the hydraulic pump arranged in the nacelle and the hydraulic
motor arranged in the tower, wherein the operating-oil line comprises the
first piping, the second piping and the connection part, and wherein the
first piping is connected to the hydraulic pump and the second piping is
connected to the hydraulic motor.

3. The power generating apparatus of the renewable energy type according
to claim 1, wherein the hydraulic motor is supported on the nacelle side
and the intermediate heat exchanger is supported on the tower side,
wherein the operating-oil line includes an operating-oil circulation line
through which the operating oil circulates between the hydraulic pump and
the hydraulic motor, and an operating-oil branch line which branches from
a low-pressure side of the operating-oil circulation line and through
which the operating line returns to the operating-oil circulation line
via the intermediate heat exchanger, wherein the operating-oil branch
line comprises the first piping, the second piping and the connection
part, and wherein the first piping is connected to the operating-oil
circulation line and the second piping is connected to the intermediate
heat exchanger.

4. The power generating apparatus of renewable energy type according to
claim 1, wherein the hydraulic motor and the generator are arranged in
the nacelle and the intermediate heat exchanger is supported on the
nacelle side, wherein the cooling-medium line comprises the first piping,
the second piping and the connection part, and wherein the first piping
is connected to an intermediate heat exchanger side and the second piping
is connected to a main heat exchanger side.

5. The power generating apparatus of renewable energy type according to
claim 1, comprising: at least one first flow path in which fluid flows
from the nacelle side to the tower side; at least one second flow path in
which fluid flows from the tower side to the nacelle side; a tubular
member in which the at least one first flow and the at least one second
flow path are formed; a first jacket which is provided around the tubular
member and which includes a circular flow path which communicates with
the first piping through a first communication opening; and a second
jacket which is provided around the tubular member and which includes a
circular flow path which communicates with the second piping through a
second communication opening, wherein the first jacket and the second
jacket are fixed to the tubular member via a bearing to be freely
rotatable relative to the tubular member.

6. The power generating apparatus of renewable energy type according to
claim 5, wherein, the tubular member has a cable-housing piping on an
inner side of the first and second flow paths, the cable-housing piping
housing a cable extending from the nacelle side to the tower side.

7. The power generating apparatus of renewable energy type according to
claim 1, further comprising: a water supply source which supplies water
to the cooling-medium line; and a pump which circulates cooling-medium in
the cooling-medium line, the cooling-medium being formed by adding
antifreeze to the water.

8. The power generating apparatus of renewable energy type according to
claim 7, wherein the water supply source is a cooling-medium tank which
stores the cooling medium, and wherein the cooling-medium tank is
arranged in an upper part of the tower and opens to a space inside the
tower.

9. The power generating apparatus of renewable energy type according to
claim 7, wherein the water supply source is a cooling-medium tank which
stores the cooling medium, and wherein the cooling-medium tank is
arranged in an upper part of the tower and is sealed off from a space
inside the tower.

10. The power generating apparatus of renewable energy type according to
claim 1, further comprising: a casing which houses the main heat
exchanger and has an inlet for the cool water source; and a filter which
is provided at the inlet for the cool water source of the casing to
prevent foreign objects contained in the cool water source from entering
the casing.

11. The power generating apparatus of renewable energy type according to
claim 1, wherein the main heat exchanger is arranged on a base on which
the tower is installed.

12. The power generating apparatus of renewable energy type according to
claim 11, further comprising: a flow-rate regulating structure which is
provided around a heat exchanger tube of the heat exchanger to regulate a
flow rate of the cool water source, wherein a distance between the
flow-rate regulating structure and the heat exchanger tube has an upper
limit which is set based on a distance at which a set heat transfer
coefficient is achieved in the heat exchanger tube, and a lower limit
which is set based on a distance at which foreign objects adhered to the
heat exchanger tube is detached.

13. The power generating apparatus of renewable energy type according to
claim 11, further comprising: a spray nozzle which sprays the cool water
source to a surface of a heat exchanger tube of the main heat exchanger.

14. The power generating apparatus of renewable energy type according to
claim 11, wherein the heat exchanger is a multitube heat exchanger having
a plurality of heat exchanger tubes.

15. The power generating apparatus of renewable energy type according to
claim 1, wherein the power generating apparatus of renewable energy type
is a wind turbine generator, wherein the tower extends upward in a
vertical direction from the base portion toward the tip portion, and
wherein the main shaft rotates upon receiving wind on the blade.

16. The power generating apparatus of renewable energy type according to
claim 1, further comprising: a generator cooler which is housed in the
nacelle and which cools the generator by air drawn in from a periphery of
the nacelle.

17. A power generating apparatus of renewable energy type which generates
power from renewable energy, comprising: a tower; a nacelle which is
supported rotatably at a tip portion of the tower; a main shaft which is
housed in the nacelle and rotates with a blade; a hydraulic pump which is
housed in the nacelle and is driven by rotation of the main shaft; a
hydraulic motor which is driven by operating oil supplied from the
hydraulic pump; a generator which is coupled to the hydraulic motor; an
operating-oil circulation line which is provided between the hydraulic
pump and the hydraulic motor and through which the operating oil
circulates; a main heat exchanger which cools the operating oil by heat
exchange with cool water source which is one of sea water, lake water,
river water and groundwater around a base portion of the tower; and an
operating-oil branch line which branches from the operating-oil
circulation line, wherein one of the operating oil circulation line and
the operating-oil branch line comprises: a first piping which is
supported on a nacelle side; a second piping which is supported on a
tower side; and a connection part which connects the first piping and the
second piping so that the first piping and the second piping are
relatively rotatable.

18. The power generating apparatus of renewable energy type according to
claim 17, further comprising: a generator cooler which is housed in the
nacelle and which cools the generator by air drawn in from a periphery of
the nacelle.

[0002] The present invention relates to a power generating apparatus of
renewable energy type which transmits rotation energy of a rotor from a
renewable energy source to a generator, particularly a power generating
apparatus of a renewable energy type having a function of cooling a
hydraulic transmission.

BACKGROUND ART

[0003] From the perspective of preserving the global environment, power
generating apparatuses of a renewable energy type such as a wind turbine
generator using wind power and a tidal generator using tidal current,
river current or ocean current energy are becoming popular. To improve
power generation efficiency, it is desired to increase the size of the
power generating apparatus of the renewable energy type. Particularly,
wind turbine generators installed offshore are expensive to construct in
comparison to those installed onshore and thus, it is desired to improve
power generation efficiency by increasing the size of the wind turbine
generator so as to improve profitability.

[0004] In the case of the power generating apparatus of renewable energy
type equipped with a mechanical gearbox, weight and cost of the gearbox
tends to increase with increase in size of the apparatus. Thus, a power
generating apparatus equipped with a hydraulic transmission having a
hydraulic pump and a hydraulic motor, instead of the mechanical gearbox,
is becoming popular.

[0005] As the power generating apparatus of renewable energy type equipped
with the hydraulic transmission, a wind turbine generator having a
hydraulic pump, a hydraulic motor and a generator in a nacelle is
introduced in Patent Literature 1, for example. In the wind turbine
generator, a rotation energy of a rotor is transmitted to the generator
via the hydraulic transmission (see FIG. 7 of Patent Literature 1).

[0006] A wind turbine generator disclosed in Patent Literature 2 has a
hydraulic pump installed in the nacelle, and a hydraulic motor and a
generator installed at a bottom of a tower and the hydraulic pump and the
hydraulic motor are connected by a piping.

[0007] Meanwhile, with increased output of the generator produced by the
larger wind turbine generator, heat loss from the generator increases. In
the wind turbine generator having the hydraulic transmission formed by
the hydraulic pump and the hydraulic motor, in addition to the heat loss
from the generator, there is heat loss from the hydraulic transmission.
Thus, a wind turbine generator having a function of cooling a
heat-producing component such as the generator and the hydraulic
transmission is desired.

[0008] In view of this, Patent Literature 3 proposes a wind turbine
generator having a cooling system for cooling a converter, a transformer
and a control unit. The cooling system includes a plurality of heat
exchangers installed around a tower. In the heat exchangers, a cooling
medium having cooled the converter, the converter, the transformer and
the control unit is cooled by heat exchange with atmospheric air.

[0009] Patent Literature 4 discloses a cooling device for a wind turbine
generator. The cooling device has a heat exchanger to cool a plurality of
devices such as a converter, a transformer, a bearing box and a
generator. Cooling water cools the devices and then is cooled by the heat
exchanger installed on an outer wall of a tower and a nacelle.

CITATION LIST

Patent Literature

[Patent Literature 1]

[0010] WO 2007/053036

[Patent Literature 2]

[0010][0011] WO 2009/064192

[Patent Literature 3]

[0011][0012] EP 1798414A

[Patent Literature 4]

[0012][0013] EP 2007184A

SUMMARY OF INVENTION

Technical Problem

[0014] Normally, a power generating apparatus of renewable energy type,
which generates electric power from renewable energy such as wind power,
tidal current, river current and ocean current, is installed where there
is significant temperature change of a surrounding environment such as
temperature of ambient air, water and so on. This changes a temperature
of an operating oil of the hydraulic transmission. The viscosity of the
operating oil changes in accordance with the temperature change. At a low
temperature, the viscosity of the operating oil becomes high, resulting
in significant energy loss in the hydraulic transmission. At a high
temperature, the viscosity of the operating oil decreases, resulting in
accelerating degradation of the operating oil. This leads to a decline of
the lubricating property, wear of the sliding part and leaking of the
operating oil. Therefore, in the power generating apparatus installed
with the hydraulic transmission, it is desired to keep the operating oil
at an appropriate temperature. However, such technique is not disclosed
in the prior art such as Patent Literatures 3 and 4.

[0015] In the cooling system disclosed in Patent Literatures 3 and 4 cool
the cooling medium by heat exchange with ambient air after the cooling
medium is used to cool the heat generating source. However, air-cooling
in general does not have high heat-exchange efficiency compared to water
cooling. Thus, it was necessary to use a larger fan for drawing in more
ambient air or to be installed a plurality of fans.

[0016] In view of the above issues, it is an object of the present
invention is to provide a power generating apparatus of renewable energy
type installed with a cooling mechanism which is capable of efficiently
cooling the operating oil of the hydraulic transmission.

Solution to Problem

[0017] As one aspect of the present invention, a power generating
apparatus of renewable energy type which generates power from renewable
energy, may include, but is not limited to: a tower; a nacelle which is
supported rotatably by a tip portion of the tower; a main shaft which is
housed in the nacelle and rotates with a blade; a hydraulic pump which is
housed in the nacelle and is driven by rotation of the main shaft; a
hydraulic motor which is driven by operating oil supplied from the
hydraulic pump; a generator which is coupled to the hydraulic motor; an
operating-oil line which is provided between the hydraulic pump and the
hydraulic motor and through which the operating oil circulates; a
cooling-medium line through which cooling medium for cooling the
operating oil circulates via an intermediate heat exchanger; and a main
heat exchanger which cools the cooling medium by heat exchange with cool
water source which is one of sea water, lake water, river water and
groundwater around a base portion of the tower, and one of the
operating-oil line and the cooling-medium line may include, but is not
limited to: a first piping which is supported on a nacelle side; a second
piping which is supported on a tower side; and a connection part which
connects the first piping and the second piping so that the first piping
and the second piping are relatively rotatable.

[0018] According to the aspect of the present invention, the cooling
medium used to cool the operating oil, is cooled by heat exchange with
the cool water source which is one of sea water, lake water, river water
and groundwater around the base portion of the tower and thus, the
cooling medium can be cooled by the cool water with high efficiency.

[0019] Further, one of the operating-oil line and the cooling-medium line
is divided into the first piping supported on the nacelle side and the
second piping supported on the tower side and the first piping and the
second piping are arranged relatively rotatable with each other by means
of the connection part having the swivel structure. Therefore, even when
the nacelle turns, the fluid can communicate smoothly between the first
piping on the nacelle side and the second piping on the tower side

[0020] In the above power generating apparatus of renewable energy type,
the hydraulic motor may be provided between the tip portion and the base
portion of the tower, the operating-oil line may extend between the
hydraulic pump arranged in the nacelle and the hydraulic motor arranged
in the tower, the operating-oil line may include the first piping, the
second piping and the connection part, and the first piping may be
connected to the hydraulic pump and the second piping is connected to the
hydraulic motor.

[0021] In this manner, by arranging the hydraulic motor between the tip
portion and the base portion of the tower, the operating-oil line extends
to the tower side. Thus, the heat exchange can be performed between the
operating oil and the cooling medium in the tower. Therefore, it is no
longer necessary to extend the cooling-medium line for cooling the
operating oil to the nacelle. Hence, in comparison to the case in which
the cooling medium is pumped to the nacelle height by the cooling-medium
line, it is possible to reduce the input of the pump and to downsize the
pump.

[0022] Alternatively, in the above power generating apparatus of the
renewable energy type, the hydraulic motor may be supported on the
nacelle side and the intermediate heat exchanger is supported on the
tower side, the operating-oil line may include an operating-oil
circulation line through which the operating oil circulates between the
hydraulic pump and the hydraulic motor, and an operating-oil branch line
which branches from a low-pressure side of the operating-oil circulation
line and through which the operating-oil line returns to the
operating-oil circulation line via the intermediate heat exchanger, the
operating-oil branch line may include the first piping, the second piping
and the connection part, and the first piping may be connected to the
operating-oil circulation line and the second piping is connected to the
intermediate heat exchanger.

[0023] In this manner, by supporting the hydraulic motor on the nacelle
side and connecting the operating-oil branch line branching from the
low-pressure side of the operating-oil circulation line to the
intermediate heat exchanger on the tower side, the operating-oil
circulation line where the flow amount of the operating oil is large can
be shorter while reducing the flow amount of the operating oil passing
through the connection part. By this, the piping structure can be
simplified. Further, the operating-oil branch line branches from the low
pressure side of the operating-oil circulation line and thus, the
operating-oil branch line and the connection part 100 can be formed by a
piping of low pressure-resistance, resulting in cost reduction.

[0024] Alternatively, in the above power generating apparatus of renewable
energy type, the hydraulic motor and the generator may be arranged in the
nacelle and the intermediate heat exchanger is supported on the nacelle
side, the cooling-medium line may include the first piping, the second
piping and the connection part, and the first piping may be connected to
an intermediate heat exchanger side and the second piping is connected to
a main heat exchanger side.

[0025] In this manner, by arranging the hydraulic motor and the generator
in the nacelle and by connecting the cooling-medium line via the
connection part to the intermediate heat exchanger supported on the
nacelle side, the connection part can be formed by a piping of low
pressure-resistance, resulting in cost reduction.

[0026] The above power generating apparatus of renewable energy type may
include, but is not limited to: at least one first flow path in which
fluid flows from the nacelle side to the tower side; at least one second
flow path in which fluid flows from the tower side to the nacelle side; a
tubular member in which the at least one first flow and the at least one
second flow path are formed; a first jacket which is provided around the
tubular member and which includes a circular flow path which communicates
with the first piping through a first communication opening; and a second
jacket which is provided around the tubular member and which includes a
circular flow path which communicates with the second piping through a
second communication opening, and the first jacket and the second jacket
are fixed to the tubular member via a bearing to be freely rotatable
relative to the tubular member.

[0027] In the above power generating apparatus of renewable energy type,
the fluid flowing from the nacelle side to the tower side enters the
first flow path formed in the tubular member via the first communication
opening from the circular flow path of the first jacket connected to the
first piping so as to flow from the first flow path to the second piping.
Meanwhile, the fluid flowing from the tower side to the nacelle side,
enters the second flow path formed in the tubular member via the second
communication opening from the circular path of the second jacket
connected to the second piping so as to flow from the second flow path to
the first piping. The first jacket and the second jacket are arranged
relatively rotatable with respect to the tubular member via the bearing
and thus, the relative rotation between the piping on the nacelle side
and the piping on the tower side while securing the flow of the fluid
flowing from the nacelle side to the tower side and the flow of the fluid
flowing from the tower side to the nacelle side and the flow of the fluid

[0028] In the above case, the tubular member may have a cable-housing
piping on an inner side of the first and second flow paths, the
cable-housing piping housing a cable extending from the nacelle side to
the tower side.

[0029] By this, even when the nacelle turns, the cable is housed in the
cable-housing piping formed in the tubular member and thus, protected
against damage

[0030] The above power generating apparatus of renewable energy type may
include, but is not limited to: a water supply source which supplies
water to the cooling-medium line; and a pump which circulates
cooling-medium in the cooling-medium line, the cooling-medium being
formed by adding antifreeze to the water.

[0031] In this manner, by providing the water supply source which supplied
water to the cooling-medium line and the pump which circulates the
cooling-medium in the cooling-medium line, a flow rate of the circulating
cooling medium can be regulated, for instance, in accordance with a
temperature change of the ambient air or the like and the operating oil
can be maintained at a constant temperature. Further, by using the
cooling medium being formed by adding antifreeze to the water, even when
the ambient air becomes not greater than a freezing temperature of the
water, freezing of the cooling-medium is prevented and thus, the smooth
operation of the cooling mechanism can be achieved.

[0032] In the above case, the water supply source may be a cooling-medium
tank which stores the cooling medium, and the cooling-medium tank may be
arranged in an upper part of the tower and open to a space inside the
tower.

[0033] By arranging the cooling-medium tank in the upper part of the tower
and allowing the cooling medium tank to be open to the space inside the
tower, it is possible to maintain sufficient water pressure in a lower
part of the cooling-medium line and thus to positively supply the cooling
medium to the cooling devices connected to the cooling-medium line. With
use of siphon effect, it is possible to reduce the input of the pump and
to downsize the pump.

[0034] Further, in the above case, the water supply source may be a
cooling-medium tank which stores the cooling medium, and the
cooling-medium tank may be arranged in an upper part of the tower and is
sealed off from a space inside the tower.

[0035] In this manner, by arranging the cooling-medium tank inside the
tower and sealing the cooling-medium tank from the space inside the
tower, the position where the cooling-medium tank is arranged is no
longer restricted. For instance, the cooling-medium tank may be arranged
in a lower part of the cooling-medium line.

[0036] The above power generating apparatus of renewable energy type may
further include: a casing which houses the main heat exchanger and has an
inlet for the cool water source; and a filter which is provided at the
inlet for the cool water source of the casing to prevent foreign objects
contained in the cool water source from entering the casing.

[0037] As described above, the cool water source is one of sea water, lake
water, river water and groundwater and the foreign objects such as marine
organisms float are included in such water. The foreign objects attached
to the heat exchanger tube of the main heat exchanger leads to a decline
of the heat exchange efficiency. Especially, attached organisms grow on
the heat exchanger tube and thus, it is unavoidable that the heat
exchange efficiency decreases gradually. In view of this, by providing
the filter in a water inlet of the casing housing the main heat
exchanger, the foreign objects are kept from entering the area around the
heat exchanger tube, thereby preventing the decline of the heat exchange
efficiency.

[0038] In the above power generating apparatus of renewable energy type,
the main heat exchanger may be arranged on a base on which the tower is
installed.

[0039] By this, the structure of the main heat exchanger on the cool water
side can be simplified.

[0040] In such case, a flow-rate regulating structure may be provided
around the heat exchanger tube of the heat exchanger to regulate a flow
rate of the cool water source, and a distance between the flow-rate
regulating structure and the heat exchanger tube may have an upper limit
which is set based on a distance at which a set heat transfer coefficient
is achieved in the heat exchanger tube, and a lower limit which is set
based on a distance at which foreign objects adhered to the heat
exchanger tube is detached.

[0041] The flow-rate regulating structure is provided around the heat
exchanger tube so as to achieve an appropriate heat transfer coefficient
as the flow rate of the cool water source flowing around the heat
exchanger tube affects the heat transfer coefficient of the heat
exchanger tube. Therefore, by setting the upper limit of the distance
between the flow-rate regulating structure and the heat exchanger tube
based on a distance at which a set heat transfer coefficient is achieved
in the heat exchanger tube, it is possible to achieve heat transfer
coefficient appropriate for cooling the cooling medium. Further, by
setting the lower limit of the distance based on a distance at which
foreign objects adhered to the heat exchanger tube is detached, it is
possible to prevent the foreign objects from accumulating on the heat
exchanger tube.

[0042] In the above case, a spray nozzle which sprays the cool water
source to a surface of a heat exchanger tube of the main heat exchanger,
may be provided.

[0043] By this, even when the foreign objects contained in the cool water
source adhere to the heat exchanger tube of the main heat exchanger, the
cool water source jetted from the spray nozzles can remove the foreign
objects from the heat exchanger tube. In this manner, the foreign objects
are physically removed by means of the spray nozzles. Thus, it is no
longer necessary to apply paint containing harmful ingredients on the
heat exchanger or to inject chorine. It is now possible to prevent the
foreign objects from adhering to or accumulating on the heat exchanger
tube and also to minimize the impact on the environment.

[0044] Alternatively, in the above case, the heat exchanger may be a
multitube heat exchanger having a plurality of heat exchanger tubes.

[0045] In this manner, the use of the multitube heat exchanger as the heat
exchanger achieves a cheap cost and increases a heat-transfer area, hence
keeping the high heat exchanger efficiency in the heat exchanger. The
heat exchanger here refers to the main heat exchanger or the intermediate
heat exchanger.

[0046] Further, the power generating apparatus of renewable energy type
may be a wind turbine generator, the tower may extend upward in a
vertical direction from the base portion toward the tip portion, and the
main shaft may rotate upon receiving wind on the blade.

[0047] The above power generating apparatus of renewable energy type may
further include a generator cooler which is housed in the nacelle and
which cools the generator by air drawn in from a periphery of the
nacelle.

[0048] In this manner, by combining the cooling of the cooling medium by
cool water and the cooling of the generator by air, it is possible to
attain an effective cooling mechanism for the power generating apparatus
of renewable energy type.

[0049] As another aspect of the present invention, a power generating
apparatus of renewable energy type which generates power from renewable
energy, may include but is not limited to: a tower; a nacelle which is
supported rotatably at a tip portion of the tower; a main shaft which is
housed in the nacelle and rotates with a blade; a hydraulic pump which is
housed in the nacelle and is driven by rotation of the main shaft; a
hydraulic motor which is driven by operating oil supplied from the
hydraulic pump; a generator which is coupled to the hydraulic motor; an
operating-oil circulation line which is provided between the hydraulic
pump and the hydraulic motor and through which the operating oil
circulates; a main heat exchanger which cools the operating oil by heat
exchange with cool water source which is one of sea water, lake water,
river water and groundwater around a base portion of the tower; and an
operating-oil branch line which branches from the operating-oil
circulation line, and

[0050] one of the operating oil circulation line and the operating-oil
branch line may include, but is not limited to: a first piping which is
supported on a nacelle side; a second piping which is supported on a
tower side; and a connection part which connects the first piping and the
second piping so that the first piping and the second piping are
relatively rotatable.

[0051] According to the other aspect of the present invention as
described, the operating oil is cooled by heat exchange with cool water
source which is one of sea water, lake water, river water and groundwater
around the base portion of the tower. Therefore, the operating oil can be
cooled by the cool water source with high efficiency.

[0052] Further, one of the operating-oil circulation line and the
operating-oil branch line is divided into the first piping supported on
the nacelle side and the second piping supported on the tower side, and
the first piping and the second piping are arranged relatively rotatable
with each other by means of the connection part having the swivel
structure. Therefore, even when the nacelle turns, the fluid can
communicate smoothly between the first piping on the nacelle side and the
second piping on the tower side.

[0053] In such case, the power generating apparatus of renewable energy
type may be provided with a generator cooler which is housed in the
nacelle and which cools the generator by air drawn in from a periphery of
the nacelle.

[0054] In this manner, by combining the cooling of the operating oil by
cool water and the cooling of the generator by air, it is possible to
attain an effective cooling mechanism for the power generating apparatus
of renewable energy type.

Advantageous Effects of Invention

[0055] In the one aspect of the present invention, the cooling medium used
to cool the operating oil, is cooled by heat exchange with the cool water
source which is one of sea water, lake water, river water and groundwater
around the base portion of the tower and thus, the cooling medium can be
cooled by cool water with high efficiency.

[0056] Further, one of the operating-oil line and the cooling-medium line
is divided into the first piping supported on the nacelle side and the
second piping supported on the tower side and the first piping and the
second piping are arranged relatively rotatable with each other by means
of the connection part having the swivel structure. Therefore, even when
the nacelle turns, the fluid can communicate smoothly between the first
piping on the nacelle side and the second piping on the tower side.

[0057] In the other aspect of the present invention, the operating oil is
cooled by heat exchange with cool water source which is one of sea water,
lake water, river water and groundwater around the base portion of the
tower. Therefore, the operating oil can be cooled by the cool water
source with high efficiency.

[0058] Further, one of the operating-oil circulation line and the
operating-oil branch line is divided into the first piping supported on
the nacelle side and the second piping supported on the tower side, and
the first piping and the second piping are arranged relatively rotatable
with each other by means of the connection part having the swivel
structure. Therefore, even when the nacelle turns, the fluid can
communicate smoothly between the first piping on the nacelle side and the
second piping on the tower side.

BRIEF DESCRIPTION OF DRAWINGS

[0059]FIG. 1 shows a general structure of a wind turbine generator in
relation to a first embodiment of the present invention.

[0060]FIG. 2A is a side view of a main heat exchanger of FIG. 1 as a
specific configuration example.

[0061]FIG. 2B is a cross-sectional view of the main heat exchanger taken
along a line A-A of FIG. 2A.

[0062]FIG. 2c is a perspective view of the main heat exchanger shown in
FIG. 2A.

[0063]FIG. 3A is a perspective view of the main heat exchanger having an
attached-object removal function.

[0064] FIG. 3B is a perspective view of the main heat exchanger having
another type of attached-object removal function.

[0065]FIG. 3C is a perspective view of the main heat exchanger having yet
another type of attached-object removal function.

[0066]FIG. 4 shows a first configuration example of a swivel structure
being applied to the wind turbine generator in relation to an embodiment
of the present invention.

[0067]FIG. 5A is a cross-sectional view taken along a line B-B of FIG. 4,
showing the first configuration example of the swivel structure of FIG.
4.

[0068]FIG. 5B is a cross-sectional view taken along a line C-C of FIG. 4,
showing the first configuration example of the swivel structure of FIG.
4.

[0069]FIG. 6 shows a second configuration example of the swivel structure
being applied to the wind turbine generator in relation to an embodiment
of the present invention.

[0070]FIG. 7 shows a third configuration example of the swivel structure
being applied to the wind turbine generator in relation to an embodiment
of the present invention.

[0071]FIG. 8 is a general view showing a first modified example of the
wind turbine generator of FIG. 1.

[0072]FIG. 9 is a general view showing a second modified example of the
wind turbine generator of FIG. 1.

[0073]FIG. 10 is a general view showing a third modified example of the
wind turbine generator of FIG. 1.

[0074]FIG. 11 shows a general structure of a wind turbine generator in
relation to a second embodiment of the present invention.

[0075]FIG. 12 shows a general structure of a wind turbine generator in
relation to a third embodiment of the present invention.

[0076]FIG. 13 shows a general structure of a wind turbine generator in
relation to a fourth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

[0077] A preferred embodiment of the present invention will now be
described in detail with reference to the accompanying drawings. It is
intended, however, that unless particularly specified, dimensions,
materials, shape, its relative positions and the like shall be
interpreted as illustrative only and not limitative of the scope of the
present invention.

First Embodiment

[0078] In a first embodiment, a wind turbine generator is described as an
example of a power generating apparatus of renewable energy type. FIG. 1
shows a general structure of the wind turbine generator in relation to
the first embodiment.

[0079] As shown in FIG. 1, the wind turbine generator 1 is mainly formed
by a tower 2, a nacelle 4 provided at a tip portion 2B of the tower 2, a
rotor 6 being rotated by wind, a hydraulic pump 8, a hydraulic motor 10
and a generator 12 being coupled to the hydraulic motor 10.

[0080] The wind turbine generator 1 shown in FIG. 1 is an offshore wind
turbine generator installed at a sea level SL. However, this is not
limitative and the wind turbine generator 1 may be installed on shore
where cool water source is available nearby.

[0081] The tower 2 is installed upright on a base 3 which is arranged at a
height near the seal level. The tower 2 extends upward from a base
portion 2A facing the base 3 to the tip portion 2B in a vertical
direction. The nacelle 4 is provided on the tip portion 2B of the tower
2.

[0082] The nacelle 4 has a baseplate 16 which is rotatably supported by
the tip portion 2B of the tower 2 via a nacelle bearing 18. Specifically,
the nacelle baseplate 16 is fixed to an inner race 18A of the nacelle
bearing 18 and the tip portion 2B of the tower is fixed to an outer race
18B of the nacelle bearing 18.

[0083] A nacelle swivel mechanism 19 is installed to the nacelle baseplate
16 and a yaw driving mechanism 13 is mounted on the nacelle baseplate 16.
By means of the nacelle swivel mechanism 19 and the yaw driving mechanism
13, the nacelle baseplate 16 swivel with respect to the tip portion 2B of
the tower 2.

[0084] The nacelle swivel mechanism 19 may be formed, for instance, by an
internal gear 19B provided on an inner periphery of the tip portion 2B of
the tower 2 and a gear 19A meshing with the internal gear 19B.

[0085] The yaw driving mechanism 13 may be, for instance, directly coupled
to a shaft of the gear 19A or formed by a reducer connected to the gear
19A via a pinion, a clutch, a yaw motor, an electromagnetic break, and a
housing which houses these components.

[0086] With the above structure, when the electromagnetic break is turned
ON in a state that the clutch is connected, a driving force of the yaw
motor is transmitted to the gear 19A via the reducer and then the gear
19A revolves while meshing with the internal gear 19B. By this, the
nacelle 4 turns with respect to the tower 2 in a yaw direction.

[0087] The nacelle 4 houses a main shaft 14 and the hydraulic pump 8
connected to the main shaft 14. The main shaft 14 is rotatably supported
by the nacelle via a main shaft bearing 15.

[0088] The rotor 6 includes a hub 6A and a plurality of blades 6B
extending radially from the hub 6A. The hub 6A of the rotor 6 is coupled
to the main shaft 14. Thus, when the rotor 6 rotates upon receiving the
wind, the main shaft rotates with the hub 6A. Then, the rotation of the
main shaft 14 is inputted to the hydraulic pump 8 and the hydraulic pump
8 generates operating oil of high pressure (high pressure oil).

[0089] The hydraulic motor 10 is arranged in a space inside the tower
between the tip portion 2B and the base portion 2A of the tower.
Preferably, the hydraulic motor 10 is arranged at a position closer to
the tip portion 2B than to the base portion 2A, i.e. on an upper side of
the tower. Meanwhile, the hydraulic motor 10 is supported on the tower
side. For instance, the hydraulic motor 10 may be mounted on a floor, a
board, a shelf or the like which is fixed to the tower 2.

[0090] The hydraulic motor 10 is driven by the high pressure oil supplied
from the hydraulic pump 8 arranged in the nacelle 4.

[0091] The generator 12 connected to the hydraulic motor 10 via an output
shaft, is also supported on the tower side. The generator 12 may be also
mounted on a floor, a board, a shelf or the like.

[0092] A relative position between the hydraulic motor 10 and the
generator 12 may be horizontal to each other or vertical to each other as
shown in FIG. 1.

[0093] An operating-oil line 30 is provided between the hydraulic pump 8
and the hydraulic motor 10 and the operating oil flows in the
operating-oil line 30.

[0094] The operating-oil line 30 includes a high-pressure side piping
through which the high pressure oil is supplied from the hydraulic pump 8
to the hydraulic motor 10, and a low-pressure side piping through which
the operating oil of low pressure (low pressure oil) is supplied from the
hydraulic motor 10 to the hydraulic pump 8.

[0095] The high-pressure side piping is formed by a first high-pressure
side piping 31 (first HP piping) which is supported on the nacelle side,
a second high-pressure side piping 32 (second HP piping) which is
supported on the tower side. Between the first HP piping 31 and the
second HP piping 32, a connection part 100 is provided. The connection
part 100 has a swivel structure and the first HP piping 31 and the second
HP piping 32 are connected by the connection part 100 so as to be
relatively rotatable.

[0096] The low-pressure side piping is formed by a first low-pressure side
piping 34 (first LP piping) which is supported on the nacelle side, a
second low-pressure side piping 33 (second LP piping) which is supported
on the tower side. Between the first LP piping 34 and the second LP
piping 33, the connection part 100 is provided. The first LP piping 34
and the second LP piping 33 are connected by the connection part 100 so
as to be relatively rotatable.

[0097] The connection part 100 having the swivel structure is arranged at
a rotation center of the nacelle 4. The configuration of the connection
part 100 is described later in detail.

[0098] The operating-oil line 30 also includes an operating-oil branch
line 35 through which at least a part of the low pressure oil from the
second LP piping 33 is fed to an intermediate heat exchanger 52 and the
low pressure oil discharge from the intermediate heat exchanger 52
returns to the second LP piping 33. The operating oil branched from the
operating-oil branch line 35 is cooled by heat exchange with
cooling-medium in the intermediate heat exchanger 52 and returns to the
second LP piping 33.

[0099] The hydraulic pump 8 is driven by the main shaft 14 and generates
the high pressure oil. The high pressure oil is supplied to the hydraulic
motor 10 via the high-pressure side piping to drive the hydraulic motor
by the high pressure oil. Meanwhile, the generator 12 coupled to the
hydraulic motor 10 is driven and the generator 12 generates electric
power. The low pressure oil discharged from the hydraulic motor 10 is
supplied to the hydraulic pump 8 via the low-pressure side piping. The
low pressure oil is pressurized again by the hydraulic pump 8 to generate
the high pressure oil and the high pressure oil is fed to the hydraulic
motor 10.

[0100] In the embodiment, a cooling mechanism is also provided to cool the
operating oil flowing in the operating-oil line 30. The cooling mechanism
may be used for a variety of cooling devices for cooling a
heat-generating source in the nacelle 4 or in the tower 2. The cooling
mechanism is now described in detail.

[0101] The cooling mechanism mainly includes a main heat exchanger 51, the
intermediate heat exchanger 52 and a cooling-medium line 40.

[0102] The main heat exchanger 51 cools the cooling medium by heat
exchange with cool water source which is one of sea water, lake water,
river water and groundwater around the base portion 2A of the tower 2. In
the offshore wind turbine generator shown in FIG. 1, the main heat
exchanger 51 is installed to the base 3 of the tower 2 and is configured
to cool the cooling medium by heat exchange with the sea water. This
simplifies a piping structure of the cool water side of the main heat
exchanger 51.

[0103] The intermediate heat exchanger 52 is arranged in the tower 2 and
cools the operating oil by heat exchange with the cooling medium.

[0104] The cooling-medium line 40 is arranged in the tower 2 and is a
closed loop through which the cooling medium for cooling the operating
oil circulates. As the cooling medium, water, oil, water to which
antifreeze is added, or the like may be used. Specifically, the
cooling-medium line 40 includes a cooling-medium supply line 41 which is
provided between the main heat exchanger 51 and the intermediate heat
exchanger 52 and through which the cooling medium having been cooled by
the sea water in the main heat exchanger 51 is supplied to the
intermediate heat exchanger 52, and a cooling-medium return line 42 which
is provided between the intermediate heat exchanger 52 and the main heat
exchanger 51 and through which the cooling medium after cooling the
operating oil in the intermediate heat exchanger 52 returns to the main
heat exchanger 51.

[0105] The cooling-medium line 40 includes a cooling-medium branch line 43
which branches from the cooling-medium supply line 41 and through which
the cooling medium returns to the cooling-medium return line 42. In the
cooling-medium branch line 43, a generator cooler 53 is provided to cool
the generator 12.

[0106] The generator cooler 53 may be configured, for instance, as a
cooling jacket formed around the generator 12. The generator cooler 53
cools the generator 12 by heat exchange with the cooling medium supplied
from the cooling-medium branch line 43.

[0107] The cooling-medium line 40 includes another cooling-medium branch
line 44 which branches from the cooling-medium supply line 41 and joins
the cooling-medium return line 42 in a manner similar to the
cooling-medium branch line 43. In the cooling-medium branch line 44, a
tower cooler 54 is provided to cool the space inside the tower 2.

[0108] The tower cooler 54 is configured as a heat exchanger installed
with a fan and a group of heat exchanger tubes. In the tower cooler 54,
the air drawn in (or forced out) by the fan in the tower 2 is cooled by
heat exchange with the cooling medium supplied to the group of heat
exchanger tubes from the cooling-medium branch line 44. By this, it is
possible to effectively cool the air in the tower 2, which is heated by
thermal discharge from the heat generating source installed in the tower
2 of the wind turbine generator 1.

[0109] Further, the cooling-medium line 40 includes a cooling-medium
branch line 45 which branches from the cooling-medium branch line 44 and
joins the cooling-medium return line 42. In the cooling-medium branch
line 45, a transformer-housing cooler 55 is provided to cool a space
inside a transformer housing 21. The transformer housing 21 herein is a
space where the transformer for transforming the electric power generated
in the generator.

[0110] The transformer-housing cooler 55 is configured as a heat exchanger
installed with a fan and a group of heat exchanger tubes. In the
transformer-housing cooler 55, the air drawn in (or forced out) by the
fan in the transformer housing 21 is cooled by heat exchange with the
cooling medium supplied to the group of heat exchanger tubes from the
cooling-medium branch line 45.

[0111] In the cooling-medium line 40, a cooling-medium tank 48 for storing
the cooling medium and a pump for circulating the cooling medium are
provided. By means of the cooling-medium tank 48 and the pump 47, a flow
rate of the circulating cooling medium can be regulated, for instance, in
accordance with a temperature change of the ambient air or the like. In
this manner, the operating oil can be maintained at a constant
temperature.

[0112] The cooling-medium tank 48 is arranged in the upper part of the
tower 2, specifically in the upper part in the height direction of the
cooling-medium line 40, and opens to the space inside the tower 2. In
this manner, by arranging the cooling-medium tank 48 in the upper part of
the tower 2 and allowing the cooling-medium tank 48 open to the space
inside the tower 2, it is possible to maintain sufficient water pressure
in a lower part of the cooling-medium line 40 and thus to positively
supply the cooling medium to the cooling devices connected to the
cooling-medium line (e.g. the intermediate heat exchanger 52, the
generator cooler 53, the tower cooler 54, the transformer-housing cooler
55). With use of siphon effect, it is possible to reduce the input of the
pump 47 and to downsize the pump 47.

[0113] The main heat exchanger 51 described above may include the
configuration shown in FIG. 2A to FIG. 2c. FIG. 2A is a side view of the
main heat exchanger of FIG. 1 as a specific configuration example. FIG.
2B is a cross-sectional view of the main heat exchanger taken along the
line A-A of FIG. 2A. FIG. 2c is a perspective view of the main heat
exchanger shown in FIG. 2A.

[0114] As shown in FIG. 2A through FIG. 2c, the main heat exchanger 51 is
provided with a heat exchanger tube 511 through which the cooling medium
flows from the cooling-medium line 40 and the sea water flows around the
heat exchanger tube 511. Hence, there is no need to provide a piping for
streaming the sea water. Further, around the heat exchanger tube 511 of
the main heat exchanger 51, a flow-rate regulating structure is provided
to regulate a flow rate of the sea water. The flow-rate regulating
structure is provided around the heat exchanger tube 511 so as to achieve
an appropriate heat transfer coefficient as the flow rate of the sea
water flowing around the heat exchanger tube 511 affects the heat
transfer coefficient of the heat exchanger tube.

[0115] For example, concrete blocks 501 for regulating the flow rate may
be provided around the heat exchanger tube 511. The flow-rate regulating
blocks 501 are arranged in a circle and between the adjacent blocks 501,
sea water ports are formed to allow for inflow and outflow of the sea
water. In a space surrounded by the flow-rate regulating blocks 501, the
sea water enters through the sea water ports 502 and flows around the
heat exchanger tube 511 to cool the cooling medium. Then the sea water
exits the space through the sea water ports 502 to outside. The flow-rate
regulating blocks 501 maintains the flow rate of the sea water around the
heat exchanger tube 511 and also blocks foreign objects contained in the
sea water from contacting the heat exchanger tube 511.

[0116] Further, a distance between the flow-rate regulating block 501 and
the heat exchanger tube 511 has an upper limit which is set based on a
distance at which a set heat transfer coefficient is achieved in the heat
exchanger tube 511, and a lower limit which is set based on a distance at
which foreign objects adhered to the heat exchanger tube 511 is detached.

[0117] By setting the upper limit of the distance between the flow-rate
regulating block 501 and the heat exchanger tube 511 based on the
distance at which a set heat transfer coefficient is achieved in the heat
exchanger tube 511, it is possible to achieve the heat transfer
coefficient appropriate for cooling the cooling medium.

[0118] Meanwhile, by setting the lower limit of the distance between the
flow-rate regulating block 501 and the heat exchanger tube 511 based on
the distance at which foreign objects adhered to the heat exchanger tube
511 is detached, it is possible to prevent the foreign objects from
accumulating on the heat exchanger tube 511. When the foreign objects
such as marine organisms adhere to and accumulate on the heat exchanger
tube 511, the heat transfer coefficient decrease. In the embodiment, by
securing a certain amount of space around the heat exchanger tube 511,
the foreign objects accumulated on the heat exchanger tube 511 become
detached. Thus, by setting the lower limit of the distance to secure such
space, it is possible to prevent the foreign objects from accumulating on
the heat exchanger tube 511.

[0119] Any type of heat exchanger may be used as the main heat exchanger
51. For the purpose of achieving a cheap cost and also increasing a
heat-transfer area, a multitube heat exchanger having a plurality of heat
exchanger tubes 511 is preferable. By this, it is possible to keep the
high heat exchange efficiency in the main heat exchanger 511. In a
similar manner, the intermediate heat exchanger 52 may be a multitube
heat exchanger having a plurality of heat exchanger tubes.

[0120]FIG. 3A is a perspective view of the main heat exchanger having an
attached-object removal function. As shown in the drawing, the main heat
exchanger 51 is provided with spray nozzles 521 each of which sprays the
sea water to a surface of the heat exchanger tube 511. The spray nozzles
521 are provided around the heat exchanger tube 511. Each of the spray
nozzles 521 is connected to a header 522. The sea water pumped by the
pump 523 is supplied to the spray nozzles 521 via the header 522 and
sprayed through the spray nozzles 521 to the surface of the heat
exchanger tubes 511.

[0121] By this, even when the foreign objects contained in the sea water
adhere to the heat exchanger tube 511 of the main heat exchanger 51, the
sea water jetted from the spray nozzles 421 can remove the foreign
objects from the heat exchanger tube 511.

[0122] FIG. 3B is a perspective view of the main heat exchanger having
another type of attached-object removal function. In the drawing, the
cooling-medium supply line 41, the cooling-medium return line 42 and the
pump 47 are not shown. This heat exchanger 51' is arranged around the
heat exchanger tube 511. The heat exchanger 51' includes a perforated
header 525 having a plurality of openings 536 formed on one side of the
perforated header 525. The sea water pumped by the pump 523 is jetted
from the openings 526 and the jet flow is supplied around the heat
exchanger tube 511. The jet flow removes the foreign objects adhered to
or accumulated on the heat exchanger tube 511.

[0123] In this manner, the foreign objects are physically removed by means
of the spray nozzles 521 or the perforated header 525. Thus, it is no
longer necessary to apply paint containing harmful ingredients on the
heat exchanger or to inject chorine in order to remove the foreign
objects. It is now possible to prevent the foreign objects from adhering
to or accumulating on the heat exchanger tube 511 and also to minimize
the impact on the environment.

[0124]FIG. 3C is a perspective view of the main heat exchanger having yet
another type of attached-object removal function. In FIG. 3C, the
cooling-medium supply line 41, the cooling-medium return line 42 and the
pump 47 are not shown. The main heat exchanger 51' is configured such
that the heat exchanger tube 511 is housed in a casing 527. In the casing
527, a sea water inlet 528 and a sea water outlet 529 are formed.
Further, the sea water inlet 528 has a filter 528a to prevent the foreign
objects contained in the sea water from entering the casing 527. As
described above, the foreign objects such as marine organisms float in
the sea water and the foreign objects attached to the heat exchanger tube
511 of the main heat exchanger 51 leads to a decline of the heat exchange
efficiency. Especially, when the marine organisms adhere to the heat
exchanger tube 511, the marine organisms grow there and thus, it is
unavoidable that the heat exchange efficiency decreases gradually.
Therefore, by providing the filter 528a in the sea inlet 528 of the
casing 527 housing the main heat exchanger 51, the foreign objects are
kept from entering the area around the heat exchanger tube 511, thereby
preventing the decline of the heat exchange efficiency. In the same
manner, a filter 529a may be provided in the sea water outlet 529. The
filters 528a and 529a are preferably configured interchangeable with each
other.

[0125] Next, a detailed configuration example of the connection part 100
is explained in reference to FIG. 4 through FIG. 7.

[0126]FIG. 4 shows a first configuration example of a swivel structure
being applied to the wind turbine generator in relation to the embodiment
of the present invention. FIG. 5A is a cross-sectional view taken along a
line B-B of FIG. 4, showing the first configuration example of the swivel
structure of FIG. 4. FIG. 5B is a cross-sectional view taken along a line
C-C of FIG. 4, showing the first configuration example of the swivel
structure of FIG. 4.

[0127] The connection part 100 of the swivel structure in the first
configuration example, has a tubular member 111 which extends in the
axial direction of the tower 2 and a first jacket 112 and a second jacket
115 which are provided around the tubular member 111. By the tubular
member 111 and the first and second jackets 112 and 115, a first flow
path 121 in which the high pressure oil flows from the hydraulic pump 8
on the nacelle side to the hydraulic motor 10 on the tower side, and a
second flow path 122 in which the low pressure oil flows from the
hydraulic motor 10 to the hydraulic pump 8 are formed.

[0128] The tubular member 11 has a double-tube structure formed by an
outer tube 111A, an inner tube 111B and a partition wall 111C. The
partition wall 111C divides a circular space formed by the outer tube
111A and the inner tube 111B in a circumferential direction to create a
plurality of arc-shaped flow paths 114a and 114b. FIG. 4B shows two
arc-shaped flow paths 114a and 114b. However, this is not limitative and
more than two flow paths may be formed.

[0129] The first jacket is provided around the outer tube 111A of the
tubular member 111. By an inner wall surface of the first jacket 112 and
an outer wall surface of the outer tube 111A, a circular flow path 112a
is formed. The circular flow path 112a is in communication with the first
HP piping 31 connected to the outer periphery of the first jacket 112.
The circular flow path 112a is in communication with the arc-shaped flow
path 114a via a first communication opening 113. Further, the arc-shaped
flow path 114a is in communication with the second HP piping 32 connected
to the outer periphery of the outer pipe 111A. In this manner, the flow
path 121 is formed by the circular flow path 112a and the arc-shaped flow
path 114a. The high pressure oil supplied from the first HP piping 31 to
the first flow path 121 flows through the circular flow path 112a, the
first communication opening 113 and the arc-shaped flow path 114a and is
supplied to the second HP piping 32.

[0130] The second jacket 115 is provided on an outer circumferential side
of the outer tube 111A of the tubular member 111 and closer to the
nacelle side than the first jacket 112 is. The second jacket 115 is
fastened to the first jacket 112 by a bolt 125. The arc-shaped flow path
114b of the tubular member 111 is in communication with the second LP
piping 33 connected to the outer periphery of the outer tube 111A.
Further, the arc-shaped member is in communication with the circular flow
path 115a formed between the inner wall surface of the second jacket 115
and the outer wall surface of the outer tube 111A via a second
communication opening 116 formed in the outer tube 111A. Further, the
circular flow path 115a is in communication with the first LP piping 34
connected to the outer periphery of the second jacket 115. In this
manner, the second flow path 122 is formed by the arc-shaped flow path
114b and the circular flow path 115a. The low pressure oil supplied from
the second LP piping 33 to the second flow path 122 flows through the
arc-shaped flow path 114b, the second communication opening 116 and the
circular flow path 115a and is fed to the first LP piping 34.

[0131] The first jacket 112 and the second jacket 115 are supported on the
nacelle side 4. In contrast, the tubular member 111 is supported on the
tower side. Between the first jacket 112 and the outer tube 111A, a
bearing 118 is provided to maintain liquid tightness therebetween.
Between the second jacket 115 and the outer tube 111A, a bearing 119a is
provided to maintain liquid tightness therebetween. The first jacket 112
and the second jacket 115 are mounted relatively rotatable with respect
to the tubular member 111 by means of the bearings 118 and 119.

[0132] With the above configuration, it is possible to secure the flow of
the high pressure oil flowing from the hydraulic pump 8 on the nacelle
side to the hydraulic motor 10 on the tower side 2 and a flow of the low
pressure oil flowing from the hydraulic pump 8 to the hydraulic motor 10,
and also possible to arrange the first piping (the first HP piping 31,
the first LP piping 34) and the second piping (the second HP piping 32,
the second LP piping 33) relatively rotatable. Therefore, even when the
nacelle 4 turns, the high pressure oil and the low pressure oil can
communicate between the hydraulic pump 8 in the nacelle 4 and the
hydraulic motor 10 in the tower 2 via the connection part 100.

[0133] Further, in the first configuration example, the space surrounded
by the inner tube 11B of the tubular member 111 may be used as a
cable-housing piping 124. The cable-housing piping 124 houses a cable 125
extending from the nacelle side to the tower side. In the example, the
cable-housing piping 124 houses the cable 125 such as a power cable used
for supplying power to electric utilization equipments arranged in the
nacelle 4 such as the hydraulic pump 8, a communication cable used for
controlling, a signal cable connected to measuring devices mounted to the
nacelle side, and a lightning-protection cable for discharging electric
power when the lightning strikes the blade 6B or the nacelle 4. In this
manner, by using the space surrounded by the inner tube 111B as the
cable-housing piping 124, even when the nacelle turn 4, the cable 125 is
protected against damage.

[0134]FIG. 6 shows a second configuration example of the swivel structure
being applied to the wind turbine generator in relation to the embodiment
of the present invention.

[0135] The swivel structure of the second configuration example has a
connection part 100'. The connection part 100' connects the hydraulic
pump 8 housed in the nacelle 4 and the hydraulic motor 10 housed in the
tower 2 with use of a first double tube 130 and a second double tube 140.

[0136] The first double tube 130 is fixed to the nacelle 4 and the second
double tube 140 is fixed to the tower 2. The first double tube 130 and
the second double tube 140 are relative rotatable with each other.

[0137] Now, detailed configurations of the first double tube 130 and the
second double tube 140 are explained.

[0138] The first double tube 130 includes an upper part 131 and a lower
part 133, which are fastened at a flange portion to each other by bolts
135. Further, a bearing 136 is provided between joint surfaces of the
upper part 131 and the lower part 133 to maintain liquid tightness
therebetween. The upper part 131 has a HP oil inlet which is connected at
a top to a discharge side of the hydraulic pump 8 via the first HP piping
31 (see FIG. 1). The lower part 133 includes an inner cylinder part and
an outer cylinder part which extend downward from the flange portion
fastened to the upper part 131. The outer cylindrical part has a LP oil
outlet formed on a side surface. The LP oil outlet is connected to an
intake side of the hydraulic pump 8 via the first LP piping 34 (see FIG.
1).

[0139] By a part of the lower part 133 (the inner cylindrical part) and
the upper part 131, a first inner piping 132 of the first double tube is
formed. By a part of the lower part 133 (the outer cylindrical part), a
first outer piping 134 of the first double tube 130 is formed.

[0140] Meanwhile, the second double tube 140 includes a second inner
piping 142 and a second outer piping 144 formed on the outer periphery of
the second inner piping 142. The second double tube 140 has a HP oil
outlet in a lower part thereof. The HP oil outlet is connected to the
second HP piping 32 (see FIG. 1). The second double tube 140 has a LP
inlet on a side surface. The LP oil inlet is connected to the second LP
piping 33 (see FIG. 1).

[0141] The first double tube 130 is rotatably fitted to the second double
tube 140. By fitting first double tube 130 and the second double tube 140
in this manner, a first flow path 151 where the high pressure oil flows
from the nacelle side to the tower side and a second flow path 152 where
the low pressure oil flows from the tower side to the nacelle side 4 are
formed.

[0142] Between the inner wall surface of the first inner piping 132 and
the outer wall surface of the second inner piping 142, an inner bearing
155 is provided. Further, between the inner wall surface of the first
outer piping 134 and the outer wall surface of the second outer piping
144, an outer bearing 156 is provided.

[0143] In the above wind turbine generator 1 the first double tube 130
supported on the nacelle side is rotatably connected to the second double
tube 140. By Therefore, even when the nacelle 4 turns, the high pressure
oil and the low pressure oil can communicate between the hydraulic pump 8
in the nacelle 4 and the hydraulic motor 10 in the tower 2 via the first
double tube 130 and the second double tube 140.

[0144]FIG. 7 shows a third configuration example of the swivel structure
being applied to the wind turbine generator in relation to an embodiment
of the present invention.

[0145] The swivel structure of the third configuration example has a
connection part 100''. The connection part 100'' includes a double tube
160 which extends in the axial direction of the tower 2, and a first
jacket 164 and a second jacket 166 which are provided to surround the
double tube 160. By the double tube 160 and the first and second jackets
164 and 166, formed are a first flow path 171 through which the high
pressure oil flow from the hydraulic pump 8 on the nacelle side 4 to the
hydraulic motor 10 on the tower side, and a second flow path 172 through
which the low pressure oil flows from the hydraulic motor 10 to the
hydraulic pump 8.

[0146] The double tube 160 includes an inner tube 160A and an outer tube
160B. Inside the inner tube 160A, an inner flow path is formed. Between
the inner tube 160A and the outer tube 160B, an outer flow path is
formed.

[0147] The first jacket 164 is arranged on an outer circumferential side
of the inner tube 160A. A circular flow path 164a is formed by an inner
wall surface of the first jacket 164 and an outer wall surface of the
inner tube 160A. The circular flow path 164a is in communication with the
first HP piping 31 connected to the outer periphery of the first jacket
164. The circular flow path 164a is in communication with the inner flow
path via a first communication opening 161 provided in the inner tube
160A. The inner flow path is in communication with the second HP piping
32 connected to a lower part of the inner tube 160A. And, the first flow
path 171 is formed by the circular flow path 164a and the inner flow
path. The high pressure oil supplied from the first HP piping 31 to the
first flow path 171 flows through the circular flow path 164a, the first
communication opening 161 and the inner flow path and then fed to the
second HP piping 32.

[0148] The second jacket 166 is provided on an outer circumferential side
of the outer tube 160B and closer to the tower side than the first jacket
164 is. The second jacket 166 is fastened to the first jacket 164 by a
bolt 175. The outer flow path is in communication with the second LP
piping 33 connected to the outer periphery of the outer tube 160B and
with the circular flow path 166a formed between the inner wall surface of
the second jacket 166 and the outer wall surface of the inner tube 160A.
Further, the circular flow path 166a is in communication with the first
LP piping 34 connected to the outer periphery of the second jacket 166.
In this manner, the second flow path 172 is formed by the outer flow path
and the circular flow path 166a. The low pressure oil supplied from the
second LP piping 33 to the second flow path 172 flows through the outer
flow path and the circular flow path 166a and is fed to the first LP
piping 34.

[0149] The first jacket 164 and the second jacket 166 are supported on the
nacelle side 4. In contrast, the double tube 160 is supported on the
tower side. Between the first jacket 164 and the inner tube 160A of the
double tube 160, a bearing 176 is provided to maintain liquid tightness
therebetween. Between the second jacket 166 and the outer tube 160B, a
bearing 177 is provided to maintain liquid tightness therebetween. The
first jacket 164 and the second jacket 166 are mounted relatively
rotatable with respect to the double tube 160 by means of the bearings
176 and 177.

[0150] With the above configuration, it is possible to secure the flow of
the high pressure oil flowing from the hydraulic pump 8 on the nacelle
side to the hydraulic motor 10 on the tower side 2 and a flow of the low
pressure oil flowing from the hydraulic pump 8 to the hydraulic motor 10,
and also possible to arrange the first piping (the first HP piping 31,
the first LP piping 34) and the second piping (the second HP piping 32,
the second LP piping 33) relatively rotatable. Therefore, even when the
nacelle 4 turns, the high pressure oil and the low pressure oil can
communicate between the hydraulic pump 8 in the nacelle 4 and the
hydraulic motor 10 in the tower 2 via the connection part 100.

[0151] According to the first embodiment described above, the cooling
medium used to cool the operating oil, is cooled by heat exchange with
sea water around the base portion 2A of the tower 2 and thus, the cooling
medium can be cooled by the sea water with higher efficiency than by
air-cooling.

[0152] Further, the operating-oil line 30 is divided into the first piping
supported on the nacelle side and the second piping supported on the
tower side and the first piping and the second piping are arranged
relatively rotatable with each other by means of the connection part 100,
100', 100'' having the swivel structure. Therefore, even when the nacelle
4 turns, the fluid can communicate smoothly between the first piping on
the nacelle side and the second piping on the tower side.

[0153] Furthermore, by arranging the hydraulic motor 10 between the tip
portion 2B and the base portion 2A of the tower 2, the operating-oil line
30 extends to the tower side. Thus, the heat exchange can be performed
between the operating oil and the cooling medium in the tower 2.
Therefore, it is no longer necessary to extend the cooling-medium line 40
for cooling the operating oil to the nacelle 4. Hence, in comparison to
the case in which the cooling medium is pumped to the nacelle height by
the cooling-medium line 40, it is possible to reduce the input of the
pump 47 and to downsize the pump 47.

[0154] Now, a modified example of the wind turbine generator 1 in relation
to the first embodiment as shown in FIG. 1 is explained. Only the
configuration different from first embodiment shown in FIG. 1 is
explained here.

[0155] A first modified example is shown in FIG. 8. In the first modified
example, a cooling-medium branch line 44' is provided. The cooling-medium
branch line 44' connects the transformer housing cooler 55 and the tower
cooler 54 in series. The cooling-medium branch line 44' branches from the
cooling-medium supply line 41 and joins the cooling-medium return line
42. The transformer-housing cooler 55 cools the air inside the
transformer housing 21 by heat exchange with the cooling medium flowing
in the cooling-medium branch line 44'. Next, the cooling medium
discharged from the transformer housing cooler 55 is supplied to the
tower cooler 54 to cool the air inside the tower 2 by heat exchange with
the cooling medium. The cooling medium having passed through those
coolers returns to the main heat exchanger 51. The tower cooler 54 and
the transformer-housing cooler 55 may be arranged in this order in the
cooling-medium branch line 44'. However, this is not limitative and the
coolers may be arranged in any order.

[0156] In this manner, by providing the cooling-medium line which connects
a plurality of heat-generating sources in series, the piping structure
can be simplified.

[0157] A second modified example is shown in FIG. 9. In the second
modified example, a plurality of the main heat exchangers are provided.
FIG. 9 shows two main heat exchangers 51a and 51b. However, this is not
limitative and the number of main heat exchangers is not limited to this
example. The cooling-medium return line 42 branches into two lines on an
inlet side of the main heat exchangers 51a and 51b, one line being
connected to the main heat exchanger 51a and other line being connected
to the main heat exchanger 51b. Pumps 47a and 47b for circulating the
cooling medium are provided respectively in the two lines branched from
the cooling-medium return line 42. The two lines in which the cooling
medium having been cooled in the main heat exchangers 51a and 51b flows
join at an outlet side of the main heat exchangers 51a and 51b and the
joined line is connected to the cooling-medium supply line 41. In this
manner, by providing a plurality of the main heat exchangers 51a and 51b,
the cooling effect can be enhanced. Further, the number of the main heat
exchangers may be determined by a total amount of heat generation from
the heat-generating sources which are subjects of cooling.

[0158] A third modified example is shown in FIG. 10. In the third
modified, a cooling-medium tank 49 connected to the cooling-medium line
40 is arranged inside the tower 2 and the cooling-medium tank 49 is
sealed off from a space inside the tower 2. In this manner, by arranging
the cooling-medium tank 49 inside the tower 2 and sealing the
cooling-medium tank 49 from the space inside the tower 2, the position
where the cooling-medium tank 49 is arranged is no longer restricted. For
instance, the cooling-medium tank 49 may be arranged in a lower part of
the cooling-medium line. FIG. 10 shows one cooling-medium tank 49.
However, this is not limitative and a plurality of the cooling-medium
tanks 49 may be provided, or a combination of the cooling-medium tank 49
and the cooling medium tank 48 of open-type as shown in FIG. 1 may be
provided.

Second Embodiment

[0159] A second preferred embodiment is explained in reference to FIG. 11.
FIG. 11 shows a general structure of a wind turbine generator in relation
to the second embodiment of the present invention. The wind turbine
generator 1 of the second embodiment is substantially the same as that of
the first embodiment, except for configurations of the hydraulic
transmission and the operating-oil line 30. Thus, mainly the
configurations different from the first embodiment are explained and the
components already described in the first embodiment are indicated by the
same reference numbers in FIG. 11 and are not explained further. In FIG.
11, the nacelle swivel mechanism 19 and the yaw driving mechanism 13 are
not shown.

[0160] In the wind turbine generator 1 of the second embodiment, the
hydraulic motor 10 and the generator 12 are supported on the nacelle side
and the intermediate heat exchanger 52 is supported on the tower side.

[0161] The operating-oil line 30 includes an operating-oil circulation
line through which the operating oil circulates between the hydraulic
pump 8 and the hydraulic motor 10, and an operating-oil branch line 38
which is connected to the operating-oil circulation line in parallel.

[0162] The operating-oil circulation line includes a high-pressure oil
line (HP oil line) 36 which connects an operating-oil outlet side of the
hydraulic pump 8 and an operating-oil inlet side of the hydraulic motor
10, and a low-pressure oil line (LP oil line) 37 which connects an
operating-oil outlet side of the hydraulic motor 10 and an operating-oil
inlet side of the hydraulic pump 8.

[0163] The operating-oil branch line 38 branches from the LP oil line 37
and extends from the nacelle side to the tower side via the connection
part having the swivel structure to be connected to the inlet side of the
intermediate heat exchanger 52 on the tower side. Further, the
operating-oil branch line 38 connected to the outlet side of the
intermediate heat exchanger 52 extends from the tower side to the nacelle
side via the connection part 100 to join the LP oil line 37. The
connection part 100 may have the same configuration as the first
embodiment.

[0164] A part of the low pressure oil branched from the LP oil line 37 is
fed through the operating-oil branch line 38 to the intermediate heat
exchanger 52 to cool the part of the low pressure oil by heat exchange
with the cooling-medium, and then is returned to the LP oil line 37
through the operating-oil branch line 38.

[0165] In this manner, by supporting the hydraulic motor 8 on the nacelle
side and connecting the operating-oil branch line 38 branching from the
LP oil line 37 to the intermediate heat exchanger 52 on the tower side,
the operating-oil line 30 where the flow amount of the operating oil is
large can be shorter while reducing the flow amount of the operating oil
passing through the connection part 100. By this, the piping structure
can be simplified. Further, the operating-oil branch line 38 branches
from the LP oil line 37 and thus, the operating-oil branch line 38 and
the connection part 100 can be formed by a piping of low
pressure-resistance, resulting in cost reduction.

[0166] The wind turbine generator of the second embodiment may also
include a generator cooler 53' to cool the generator 12 by air.

[0167] In such case, a duct 81 is provided on the outer periphery of the
nacelle 4 to draw in the ambient air. The duct 81 has an air inlet and is
formed integrally on a wall surface of the nacelle 4. To promote letting
in the ambient air, the duct 81 may have a fan 82 inside.

[0168] The ambient air drawn in by the duct 81 is led to the inside of the
nacelle 4 via an air piping 83. In the air piping 83, a generator cooler
53' is provided. The generator cooler 53' may be configured, for
instance, as a cooling jacket formed around the generator 12 to cool the
generator 12 by streaming in the outer periphery of the cooling jacket
the air drawn in by the duct 81. The air after cooling the generator 12
is discharged outside the nacelle through the air piping 83.

[0169] The ambient air drawn in by the duct 81 may be used to cool other
heat-generating sources inside the nacelle 4. For instance, the ambient
air may be used to cool the nacelle cooler (not shown) which cools the
air inside the nacelle. In this manner, mainly the cool water is used to
cool the heat-generating sources inside the tower 2 and the air is used
to cool the heat-generating source inside the nacelle 4. As a result, the
heat-generating sources of the wind turbine generator 1 can be cooled
efficiently.

Third Embodiment

[0170] A third preferred embodiment is explained in reference to FIG. 12.
FIG. 12 shows a general structure of a wind turbine generator in relation
to the third embodiment of the present invention.

[0171] The wind turbine generator 1 of the third embodiment is
substantially the same as that of the first embodiment, except for
configurations of the hydraulic transmission and the operating-oil line
30. Thus, mainly the configurations different from the first embodiment
are explained and the components already described in the first
embodiment are indicated by the same reference numbers in FIG. 12 and are
not explained further. In FIG. 12, the nacelle swivel mechanism 19 and
the yaw driving mechanism 13 are not shown.

[0172] In the wind turbine generator 1 of the third embodiment, the
hydraulic motor 10 and the generator 12 are arranged in the nacelle 4 and
the intermediate heat exchanger 52 is arranged in the nacelle 4 as well.

[0173] The operating-oil line 30 includes an operating-oil circulation
line through which the operating oil circulates between the hydraulic
pump 8 and the hydraulic motor 10, and an operating-oil branch line 38'
which is connected to the operating-oil circulation line in parallel.
Both of the operating-oil circulation line and the operating-oil branch
line 38' are arranged in the nacelle 4.

[0174] The operating-oil circulation line includes a high-pressure oil
line (HP oil line) 36 which connects the operating-oil outlet side of the
hydraulic pump 8 and the operating-oil inlet side of the hydraulic motor
10, and a low-pressure oil line (LP oil line) 37 which connects the
operating-oil outlet side of the hydraulic motor 10 and the operating-oil
inlet side of the hydraulic pump 8.

[0175] The operating-oil branch line 38' branches from the LP oil line 37
and is connected to the inlet side of the intermediate heat exchanger 52
arranged in the nacelle 4. Further, the operating-oil branch line 38'
connected to the outlet side of the intermediate heat exchanger 52 joins
the LP oil line 37.

[0176] The cooling-medium line 40 includes a cooling-medium supply line 41
which is provided between the main heat exchanger 51 and the intermediate
heat exchanger 52 via the connection part 100 having the swivel
structure, and a cooling-medium return line 42 which is provided between
the intermediate heat exchanger 52 and the main heat exchanger 51 via the
connection part 100 in the same manner. Further, the connection part 100
may have the same configuration as the first embodiment.

[0177] The cooling medium having been cooled by the sea water in the main
heat exchanger 51 is supplied to the intermediate heat exchanger 52
through the cooling-medium supply line 41 and cools the operating oil by
heat exchange in the intermediate heat exchanger 52 and then returns to
the main heat exchanger 51 through the cooling-medium return line 42.

[0178] In this manner the hydraulic motor 8 and the generator 10 are
arranged in the nacelle 4 and the cooling-medium line 40 is connected via
the connection part 100 to the intermediate heat exchanger 52 supported
on the nacelle side and thus, the connection part 100 can be formed by a
piping of low pressure-resistance, resulting in cost reduction.

[0179] Further, the cooling-medium line 40 may include a cooling-medium
branch line 43' which branches from a nacelle side of the cooling-medium
supply line 41 and joins a nacelle side of the cooling-medium return line
42. In the cooling-medium branch line 43', the generator cooler 53 may be
provided to cool the generator 12. The generator cooler 53 may be
configured, for instance, as a cooling jacket formed around the generator
12. In the generator cooler 53, the generator 12 is cooled by heat
exchange with the cooling medium supplied from the cooling-medium branch
line 43'.

Fourth Embodiment

[0180] A fourth preferred embodiment is explained in reference to FIG. 4.
FIG. 13 shows a general structure of a wind turbine generator in relation
to the fourth embodiment of the present invention.

[0181] The wind turbine generator 1 of the forth embodiment is not
provided with the cooling-medium line 40 and the operating oil of the
hydraulic transmission is cooled directly by the sea water. Further, the
wind turbine generator 1 of the fourth embodiment is substantially the
same as that of the first embodiment, except for configurations of the
hydraulic transmission, the operating-oil line 30 and the cooling-medium
line 40. Thus, mainly the configurations different from the first
embodiment are explained and the components already described in the
first embodiment are indicated by the same reference numbers in FIG. 13
and are not explained further. In FIG. 13, the nacelle swivel mechanism
19 and the yaw driving mechanism 13 are not shown.

[0182] In the wind turbine generator 1 of the fourth embodiment, the
hydraulic motor 10 and the generator 12 are arranged in the nacelle 4.

[0183] The operating-oil line 30 includes an operating-oil circulation
line through which the operating oil circulates between the hydraulic
pump 8 and the hydraulic motor 10, and an operating-oil branch line 70
which is connected to the operating-oil circulation line in parallel.
Both of the operating-oil circulation line and the operating-oil branch
line 70 are arranged in the nacelle 4.

[0184] The operating-oil circulation line includes a HP oil line 36 which
connects the operating-oil outlet side of the hydraulic pump 8 and the
operating-oil inlet side of the hydraulic motor 10, and a LP oil line 37
which connects the operating-oil outlet side of the hydraulic motor 10
and the operating-oil inlet side of the hydraulic pump 8.

[0185] The operating-oil branch line 70 includes the first piping 71, 74
supported on the nacelle side and a second piping 72, 73 supported on the
tower side. The operating-oil branch line 70 is preferably arranged in
parallel to the LP oil line 37. In the operating-oil branch line 70, a
pump is provided to stream the operating oil in the operating-oil branch
line 70.

[0186] The first piping 71 and the second piping 72 are connected
relatively rotatable by means of the connection part 100 having the
swivel structure. In the same manner, the first piping 73 and the second
piping 74 are connected relatively rotatable by means of the connection
part 100. The connection part 100 has the same configuration as the first
embodiment. The connection part 100 may have the same configuration as
the first embodiment.

[0187] The operating oil which branched from the LP oil line 37 is
introduced through the first piping 71, the connection part 100 and the
second piping 72 to the main heat exchanger 58 in this order. In the main
heat exchanger 58, the cooling medium is cooled by heat exchange with the
sea water. The cooling medium discharged from the main heat exchanger 58
is returned through the second piping 73, the connection part 100 and the
first piping 74 to the LP oil line 37 in this order.

[0188] According to the fourth embodiment, the operating oil is cooled by
heat exchange with cool water source which is one of sea water, lake
water, river water and groundwater around the base portion of the tower.
Therefore, the operating oil can be cooled by the cool water source with
higher efficiency than by air-cooling.

[0189] Further, one of the operating-oil circulation line and the
operating-oil branch line 70 is divided into the first piping 71, 74
supported on the nacelle side and the second piping 72, 73 supported on
the tower side and the first piping 71, 74 and the second piping 72, 73
are arranged relatively rotatable with each other by means of the
connection part 100, 100', 100'' having the swivel structure. Therefore,
even when the nacelle 4 turns, the fluid can communicate smoothly between
the first piping 71, 74 on the nacelle side and the second piping 72, 73
on the tower side.

[0190] The wind turbine generator 1 of the fourth embodiment may also
include the generator cooler 53' to cool the generator 12 by air.

[0191] In such case, the duct 81 is provided on the outer periphery of the
nacelle 4 to draw in the ambient air. The ambient air drawn in by the
duct 81 is led to the inside of the nacelle 4 via the air piping 83. In
the air piping 83, the generator cooler 53' is provided. The generator
cooler 53' may be configured, for instance, as a cooling jacket formed
around the generator 12 to cool the generator 12 by streaming in the
outer periphery of the cooling jacket the ambient air drawn in by the
duct 81. The air after cooling the generator 12 is discharged outside the
nacelle through the air piping 83.

[0192] The ambient air drawn in by the duct 81 may be used to cool other
heat-generating sources inside the nacelle 4. For instance, the ambient
air may be used to cool the nacelle cooler (not shown) which cools the
air inside the nacelle 4. In this manner, mainly the cool water is used
to cool the heat-generating sources inside the tower 2 and the air is
used to cool the heat-generating source inside the nacelle 4. As a
result, the heat-generating sources of the wind turbine generator 1 can
be cooled efficiently.

[0193] While the present invention has been described with reference to
exemplary embodiments, it is obvious to those skilled in the art that
various changes may be made without departing from the scope of the
invention.

[0194] In the above embodiments, the wind turbine generator 1 is described
as a specific example of the power generating apparatus of renewable
energy type. However, the present invention is not limited to this and is
also applicable to other types of power generating apparatuses of
renewable energy type.

[0195] For instance, the present invention may be applied to a power
generating apparatus which uses one of tidal current, ocean current and
river current to generate power and the tower of which extends upward in
the vertical direction from the base portion to the tip portion in or
under the sea and the main shaft of which rotates upon receiving one of
tidal current, ocean current and river current on the blade.